The present invention generally relates to monitoring the integrity of grounding components in an electrical system. More specifically, the present invention relates to various apparatuses and methods by which a signal may be imposed on an electrical system by a first inductive element and received by a second inductive element such that grounding system impedance may be determined and integrity of grounding components assessed.
It is well known that methods of equipment grounding are necessary to protect the equipment in an electrical system from adverse electrical effects that may result in equipment failure, such as electrical surges. Methods of equipment grounding are well known in the art and are required in most applications by the United States National Electric Code (NEC), National Fire Prevention Association (NFPA), and local codes. It is also well known that methods of earth grounding are necessary to provide an electrical system with a low impedance path to ground such that electrical energy from adverse electrical effects, such as lightning, may be dissipated and risk of personal injury from electrical shock hazards may be minimized. Methods of earth grounding are well known in the art and are generally subject to the same governing codes as equipment grounding.
Said governing codes generally require impedance measurements of the equipment and earth grounding systems, which may be completed during installation using commercially available methods. One such method utilizes portable clamp-on meters which, while functional, require onsite personnel and may be time-consuming and unreliable due to operator error and inconsistent methods of measuring. Further, clamp-on meters and other methods of measuring impedance in grounding systems are generally single channel devices that may be prohibitively expensive to utilize in an electrical system with a plurality of grounding systems or components therein.
Also challenging is that commercially available methods of measuring impedance in grounding systems produce an instantaneous measurement and do not allow for practical recurrent testing. Impedance measurements of equipment and earth grounding systems completed at the time of installation may verify adherence to governing codes, however, impedance of the grounding systems may increase over the life of the electrical system (e.g. due to corrosion or theft). In the current state of the art, to accurately measure the impedance of an equipment and earth grounding system after installation is complete, trained personnel must repeatedly return to the site with specialized equipment, which may be time-consuming and cost-prohibitive.
However, repeated impedance measurements by trained personnel returning to an application site do not ensure the overall electrical system is compliant with governing codes during periods of time between visits. The current state of the art may benefit from methods of actively monitoring the integrity of the equipment and earth grounding components of an electrical system such that changes in system impedance may be tracked, a user of the electrical system notified when system impedance increases to undesirable levels, and optionally, methods of disabling components of an electrical system in response to impedance increases. Thus, there is room for improvement in the art.